Cetirizine, [2-[(4-chlorophenyl phenylmethyl]-1-piperazinyl]ethoxy] acetic acid is a nonsedating type histamine H.sub.I receptor antagonist having antiallergic and spasmolytic action, and is described in European patents Nos. 058,146; 294,993; and 357,369; and also WO 92/02212 relates to cetirizine formulations for the controlled or continuous release of cetirizine in the form of tablets and capsules. Oral or nasal formulations, for example in the form of cough syrup, are disclosed in WO 94/08551.
Cetirizine solutions for administration at the eye and in the nose are described in European patent No. 605,203. Oral administration forms coated with at least one layer of a volatile aroma, such as are described in menthol WO 94/-25009, and freeze-dried dosage forms having a taste-masking matrix as is described in European patent No. 636,365.
European patent No. 548,356 claims multiparticulate tablets having a disintegration rate in the oral cavity or on the tongue of less than 60 seconds which contain the active ingredient in the form of coated microcrystals, particularly microgranules for masking the taste.
WO 95/07070 discloses effervescent granules for producing a pharmaceutical preparation based on calcium carbonate and citric acid, where from 5 to 20 parts by weight of the citric acid are replaced by at least one other edible acid, such as malic acid.
European patent No. 636,364 describes a dosage form which dissolves very quickly and which has active ingredient particles which are coated with a taste-masking substance, a water-soluble combinable carbohydrate and a binder. The tablet disintegrates in the mouth within 30 seconds after oral administration, so that the coated active ingredient particles can be swallowed by the patient before the active ingredient is released.
For example, mannitol, dextrose or lactose are the carbohydrates used, and for example, cellulose acetate or hydroxypropylmethylcellulose are used for masking taste.
European patent No. 525,388 discloses lozenges or chewable tablets containing the dibasic alkali metal and/or alkaline earth metal salt of a tribasic edible organic acid, preferably an edible organic acid, more specifically citric acid, such as malic acid, which is only partly converted into the alkali metal and/or alkaline earth metal salt, and also to auxiliary ingredients. It is thus intended to avoid the stale aftertaste of known lozenges or chewable tablets, in particular the prevention of the chalky taste of lozenges or chewable tablets containing mineral substances. No reference is made to any possibility of relieving a bitter aftertaste.
The active ingredient cetirizine hydrochloride has a very bitter taste and is not particularly suitable for rapidly disintegrating, solid preparations. Consequently, effervescent cetirizine formulations are not known in the prior art.
There is a need to introduce on the market effervescent pharmaceutical preparations in the form of soluble and dispersible tablets based, in particular, on a calcium-containing base. Certain elderly people may have problems with taking tablets, and there are many patients who have difficulties in swallowing. Certain rapidly disintegrating effervescent formulations have the additional advantage of portability without any liquids.
The simultaneous intake of the mineral calcium with antihistamines is also desirable for the treatment of allergies.
Masking the bitter taste of cetirizine causes particular problems. Thus, an aqueous solution of cetirizine hydrochloride has an unpleasant bitter taste. By adding suitable taste-masking substances, as described, for example, in European patent No. 636,364 and in U.S. Pat. No. 5,178,878, the preparation is complicated, and the dispersibility of microencapsulated active ingredients is considerably reduced. It is a further disadvantage that, in addition to the actual active ingredient, a large number of auxiliary ingredients are required for preparing such a formulation.
Film-coated tablets and oral solutions are available in which the film layer masks the bitter taste. The solutions contain large amounts of sorbitol flavorant (450 mg of sorbitol per mg of cetirizine).
Effervescent preparations of various active ingredients and vitamins are generally known per se in the prior art. These effervescent preparations generally contain an agent which is capable of releasing CO.sub.2, and an agent which induces the release of CO.sub.2.